stop using System.CommandLine types that won't be public anymore

[adamsitnik]

Context: dotnet/command-line-api#2563

[Copilot]

Pull Request Overview

This PR replaces obsolete System.CommandLine types by switching help extensions to use ParseResult and Action<ParseResult> instead of HelpContext and IEnumerable<Func<HelpContext, bool>>. It also centralizes the post-build help customization into a new CustomizedHelpAction.

• Change GetExtendedHelp in three root commands to void GetExtendedHelp(ParseResult) and remove legacy HelpContext-based enumerator.
• Update UseExtendedHelp extension to accept an Action<ParseResult> and wire up CustomizedHelpAction.
• Add CustomizedHelpAction implementation and an unused using import in CommandLineHelpers.cs.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
src/coreclr/tools/dotnet-pgo/PgoRootCommand.cs	Updated GetExtendedHelp signature and logic to print examples for trace
src/coreclr/tools/aot/crossgen2/Crossgen2RootCommand.cs	Updated GetExtendedHelp signature and removed legacy layout iteration
src/coreclr/tools/aot/ILCompiler/ILCompilerRootCommand.cs	Updated GetExtendedHelp signature and removed legacy layout iteration
src/coreclr/tools/Common/CommandLineHelpers.cs	Changed UseExtendedHelp to use CustomizedHelpAction and added helper

Comments suppressed due to low confidence (2)

src/coreclr/tools/Common/CommandLineHelpers.cs:133

• [nitpick] The parameter name customizer is clear, but the unused discard _ in the root commands may be confusing. Consider using a descriptive name like parseResult for consistency.

public static RootCommand UseExtendedHelp(this RootCommand command, Action<ParseResult> customizer)

src/coreclr/tools/dotnet-pgo/PgoRootCommand.cs:263

• The new GetExtendedHelp(ParseResult) behavior (especially for create-mibc and create-jittrace) lacks automated tests to verify the extended help output.

public static void GetExtendedHelp(ParseResult parseResult)

[jkotas]

This method is not returning anything after this change, so Get... name does not fit what it does anymore.

I would rename it to PrintHelp, DisplayHelp or something similar.

[jkotas]

(I have not commented on all places with this name. All of them should be fixed.)

[jkotas]

LGTM modulo a few nits